Rotary tool and turbine therefor

ABSTRACT

A rotary tool comprising a housing in which a spindle is mounted. The spindle being driven by air turbine, and having an air cushion bearing. The turbine simultaneously is provided with an air cushion bearing. Means are provided for pneumatically extending and retracting the spindle.

United States Patent 1151 3,677,351

Geissler [451 July 18, 1972 54] ROTARY TOOL AND TURBINE 3.053.503 9/1962 THEREFOR 2,671,700 3/1954 2,877,066 3/1959 [72] inventor: Ulrich M. Geisler, Ft. Lauderdale, Fla. 9 33 8/1962 Gem" 3128988 4/1964 7 I Y [3] Assume ganiafla 3,210,848 10/1965 3,293,955 12/1966 [22] Filed: Oc'l. 6, I970 [2|] Appl. No.: 78,383

Primary Examiner-James A. Leppink Attorney-Bauer & Amer 52 us. CI ..173/57, 173/168, 308/9, 1 535mm 415/503 A rotary tool comprising a housing in which a spindle is [5| Int. (J. ..B2Sd 9/00, B23b /04 mount; The 1 being driven by i turbine and having I 58] Fit 0' SGII'CII 173/57, 168; 308/DIG. 1, 9; an aj gushjon bearing The turbine simultaneously is provided 122 with an air cushion bearing. Means are provided for pneumaticaliy extending and retracting the spindle. [56] Relerences Cited ZOChinmSDrawlngHgm-ee UNITED STATES PATENTS 3,306,375 2/1967 Macks ..308/9 1 94 as {75 735 9o 7 'L/-/ no.- V 1 -26 73"" 1 28 2x a 72 j 94 v 3% I 78 1 1 34 5 11' 1/ ""1/6 .1 mm 53 v hhli a *1 #55/ 46 1 1 1/ 1 5,911 /a- 1 60 N1 f g l g g' F" 1 v 1 1/ 64 w "J/( 1 -/44 i; ,7" w 64 so 5 M 11 Hg I 44 48 (Y /4s\ 1 I 56 v 66 Q\ .1 g E 1 "436 (E 68 1 111 H 1 M24 A 1 IO -1 v Ja v 1 525A Lil 1 g I I, H

I26 I30 42 w r L f 156 I56 Patented July 18, 1972 3,677,351

3 Sheets-Sheet 1 INVENTOR. ULRICH M. GEISSLER A TTORNE YS FIG! Patented July 18, 1972 3 Sheets-Sheet :2

FIG-4 INVENTOR. ULRICH M GEISSLEF? FIG.3

A T TORNE YS Patented July 18, 1972 3,677,351

3 Sheets-Sheet 3 1 ROTARY r001. AND TURBINE THEREFOR The present invention relates to the manufacture and construction of rotary drills, sanding, grinding and milling devices and particularly to the bearing and driving means for miniature devices of this nature.

High speed automatic tools, of a miniature nature are becoming increasingly necessary in the mass production of various components for electronic, automated control equipment. The need for such tools is even apparent in the construction of miniature mechanical equipment. By miniaturization we refer to such specific items as the production of printed circuits and related components for space usage; the production of medical apparatus; and the production of precision horological instruments. in each of these the need for small size (fraction of an inch), precision tolerances with thousands and millions of an inch) and speed (well in excess of 100,000 RPM) are required.

It is most difficult, and up until now virtually impossible, to combine high speed precision, durability and miniature size in one tool. In rotary tools in particular, the high speed operation of a small spindle creates considerable friction heat and ultimate distortion. Conventional mechanical drive means are heavy, cumbersome and not capable of producing the high rotary speeds necessary to work on the very sophisticated and advanced materials used in these industries.

It is the object of this invention to provide a high speed rotary mechanism having improved precision, stability and performance characteristic over those formed in the prior art.

It is another object of the present invention to provide an improved head capable of being adapted for use as a drill, router, grinder, miller, sander, etc. in miniature operation.

it is a particular object of the present invention to provide apparatus of the type described which has improved rotary spindle bearing means of increased precision, and improved spindle drive means therefore.

These particular objects, others and many advantages will be more fully described in connection with the actual disclosure of the present invention, which is to follow.

According to the present invention a rotary tool is provided in which the spindle is held in a pneumatic bearing and in which the spindle is driven by a pneumatic turbine. In the preferred form the spindle is mounted in a bearing sleeve which is provided with a plurality of orifices through which air under pressure is fed forming a thin cushion of air between the parts. The tolerances between the spindle and the bearing sleeve are preferably in the order of millionths of an inch so that the play or sideway movement of the spindle is virtually eliminated. By providing the air bearing support of the present invention such miniature tolerances can be obtained while retaining fully free rotation of the parts.

In another aspect of the present invention, a miniature air turbine is provided which is mounted directly at the end of the spindle. The air turbine comprises a rotating wheel having a plurality of drive buckets similar to those of conventional Pelton wheels. In the preferred form the number of buckets is significantly greater than those heretofore conventional or believed necessary. The rotor wheel is provided with an equal number of air jets, unlike conventional turbines which have one or two inlet jets. This combination of plural buckets and plural corresponding nozzles provided extremely high speeds at smooth, efficient and uniform operation with greater power at less air comsumption.

In still another aspect of the present invention a unique air bearing system is provided for the turbine parts itself which also contributes increased speed and efficiency.

Still another aspect of the present invention is the provision of the pneumatic or hydraulic actuating means for feeding or stoking the working tool element toward and away from the work piece. The pneumatic system is a positive control adaptable to exert varying degrees of pressure on the tool and to maintain the tool in positive engagement during all aspects of the work operation.

The present invention is embodied in a miniature form; the parts being relatively smaller than those in known use. Various auxiliary mechanisms, such as positioning controls mounting means, etc. are also provided.

Full details of the present invention and its preferred embodiment will be seen from the following disclosure.

in the following disclosure reference is made to the accompanying drawings in which:

FIG. I is a vertical section through the rotary tool embodying the present invention,

FIG. 2 is a partial isometric perspective view partially in section showing the construction of the pneumatic turbine,

FIG. 3 is a plan view of the thrust disk providing the air cushion for the turbine,

FIG. 4 is a sectional view of the thrust disk along line 4-4, and

FIG. 5 is an exploded view showing the arrangement of supporting members and thrust disk for the turbine.

The present invention is illustrated as being embodied in a high speed drill head comprising an exterior cylindrical body 10 which may be mounted to a positionable standard for movement toward and away from a given workpiece. Alternatively, the drill head may be fixed in position and the workpiece moved toward and away from it. The various types of mountings as well as all of the associated apparatus such as the work table, positioning means and operating mechanism, are quite conventional in this art and are not shown here for the sake of brevity. The device may be used in any position; i.e., vertical or horizontal, pointed upward or downward or even at angles to the vertical or horizontal.

Located along the central axis of the body at the forward end of which is threadedly secured a chuck formed of a collet l4 and an adjustable nut 16 which holds a drill bit 18. The mounting of the drill bit and the bit itself are conventional and may be readily replaced with alternative structures. The rear end of the spindle I2 is provided with an extending threaded hub 20 to which is secured a rotatable pneumatic turbine, generally designated by numeral 22. The turbine is similar to a conventional Pelton turbine, modified for pneumatic operation and for increased speed and efficiency in a manner to be described more fully hereafter. Briefly, the turbine comprises a rotatable wheel 24 surrounded by an annular reaction ring or stator 26 sandwiched between a pair of fixed thrust disks 28 and 30. Mounted about the spindle I2 is an elongated bearing sleeve 32 which itself is surrounded by a bearing mount 34, which is secured together with the stator 26 and the thrust disks 28 and 30 to a manifold cap 36, by suitable screw fasteners 38. The upper end of the bearing mount 34 is formed with a radial collar 40 to conform to the radial size of the turbine. The lower end of the bearing mount 34 is provided with a threaded retaining ring 42. The bearing sleeve 32 and the bearing mount are swedged, press fit, keyed or otherwise joined so that they are conjointly movable.

Located about the bearing mount 34 is an axial positioning assembly generally referred to by the numeral 44 which is adapted to move the spindle l2 axially within the body 10 while maintaining it in aligned support therein. The assembly 44 comprises a subassembly formed of an inner cylinder 46 fixed between the collar 34 and retaining ring 42 of the bearing mount, a coaxially spaced outer cylinder 48 slidably abutting against the interior wall of the body 10, and upper and lower annular plugs 50 and 52 respectively threaded to the outer cylinder 48 while being slidable with respect to the inner cylinder 46. The inner and outer cylinders 46 and 48 and their end plugs 50 and 52 define between them a pneumatic chamber 54 in which an annular piston member 56 is located, the piston 56 being an integral part of the inner cylinder 46.

The upper plug 50 has a radially extending ring 58 to which a plurality of keys 60 are secured by suitable screws 62. The keys 60 have a fixed upper annular stop 64 and a fixed lower stop 66 about which is located a knurled adjustment knob 68. The knob 68 is internally threaded with a helical groove conforming to the lower stop 66 so that rotation of the knob 68 10 is a spindle l2 will cause the up and down movement of the outer cylinder 48 and plugs 50 and 52 relative to the outer body 10. impression of air in the chamber 54 to either side of the piston 56 will cause the spindle to move up or down axially with respect to the body in an automatic manner later to be described.

The construction of the turbine 22 is seen in enlarged detail in FIG. 2 and comprises an annular ring housing 72 having a pair of axial exhaust ducts 73 in which is concentrically arranged and securely fixed the reaction ring 26. The solid disklike wheel 24 is freely located within the reaction ring 26 and is sandwiched between the upper and lower thrust disks 39 and 28 respectively. The turbine is formed with a plurality of closely spaced blades in the shape of horseshoe segmented buckets 74. It has been found thirty buckets spaced uniformly about a wheel of less than [.5 inches in diameter is sufficient for the present purposes. Variations in the number of buckets will produce changes in both power and speed. For example, increasing the number of buckets produces more power but less speed while decreasing the number produces less power but higher speed. The buckets are formed by cutting a central groove 75 to the desired depth and then cutting (milling) the horseshoe segment shapes 74 with their center at the same depth and with the side wings tapering upward to the edges of the wheel the buckets 74 do not extend to the axial edges of the wheel 24.

The stator 26 as seen in FIG. 2 comprises a ring fonned with a central groove 76 on its exterior surface in which a plurality of bores 78 are drilled. The number of the bores 78 are the same or nearly the same as the number of buckets 72 formed on the wheel and drilled at an angle to the stator 26 so as to be tangent to the bottom of the groove 75 formed in the turbine wheel. As a result of this construction, both the rotatable wheel and the stator are provided with equal or near equal number of buckets and nozzles, the actual number being many more than are customary in conventional Pelton wheels. The axial exterior surfaces of the reaction ring is cut with a plurality of vanes 80, which extend circumferentially about the ring in an angular direction to the rotation of wheel 24 at either side of the nozzles 78. The vanes 80 are located to extend partially over the shallow side wings of the buckets 74 and as will be explained later provide a secondary turbine efiect with the air of the turbine wheel 24. The outer circumferential edges of the stator 26 is provided with a cut down shoulder 86 forming a groove which communicates with the exhaust ducts 73 in the housing 72.

The upper and lower thrust disks 28 and 30 respectively are drilled with a plurality of concentric axially arranged bores 88 (FIGS. 2 and 3) which are connected by intercornmunicating circumferential grooves 90 and radial ducts 92 (FIG. 2). Preferably three rings of groove 90 are employed having l0, l5 and 20 holes 88 respectively from the center outward. Each of the bores 88 is tapered and narrowed to an extremely small opening toward the surface of the rotating wheel 24. The upper disk 28 has a central milled recess 96 communicating with central duct 98 through which air from the thrust bearing exhausts. This maintains pressure at once with the lower disk 30 which has an enlarged central opening to fit over the spindie.

The manifold cap 36 is provided with four axial inlet passages 100, 102, I06 and 108, the first for supply air under pressure to the turbine 22, second for supplying air to the thrust disks 28 and 30 respectively and simultaneously to the spindle bearing sleeve 32 and the last two for supplying air to the axial position piston-cylinder assembly 44 for causing up and down movement of the spindle. Each inlet passage is provided with suitable connection means and conduits to a source of air under pressure (none of which are shown) but which are all conventional.

First to a description of the pneumatic supply and operation of the turbine. The inlet passage 100 is connected via an axial duct 110 through the upper thrust disk 38 and the turbine housing 72 to a radial duct 2 which feeds directly into the nozzle groove 76 in the exterior surface of the reaction ring 26. The air then proceeds through the nozzles 78 against the buckets 74 being forced against the circumferential groove 75 by the tangential arrangement of the nozzles. This comprises a first stage turbine reaction by which the wheel 24 is rotated. The air is then deflected from the central groove 75 along the two ends of the horseshoe shaped buckets 74 changing its direction 180 to hit against the vanes 80 of the reaction ring 26. This reverse flow and reaction with the vanes 80 form a second turbine reaction stage which adds further propulsion to the turbine wheel. The air passes through the vanes 80 into the circumferential groove 86 to exhaust through the passages 73. Because the buckets 74 do not extend to the edges of the wheel 24 there exist a neutral circumferential ring extending through the vanes 80, into which the bearing air exhausts without turbulence with the exhausting turbine air.

Simultaneously air is impressed through inlet I02 into the bores 88 of each of the upper and lower thrust disks 28 and 30. The inlet 102 communicates with a duct "4 passing through disk 28, 30 and housing 72 to communicate with the radial gooves 92 formed in each. Air is passed through the bores 88 via their tapered ends to impinge axially against the opposite faces of the wheel 24 forming a cushion about the wheel. The air exhausts radially into the space between turbine wheel and reaction ring pass through vane 88 where this air mixes with and joins the air flow exhausting for the turbine. Thus, the air flow through the bores and grooves of the thrust disks provides an improved and superior air bearing for the turbine wheel, on both sides of the wheel.

Actuation of the turbine by the combined flow of air into inlets cause the turbine to rotate at high speed, driving the spindle 12 about its own central axis. The drill bit can be operated at a variable speed from 22,000 RPM to well over l00,000 RPM at from 15 to I00 PSl at a pressure drop of only l5 PSI. In fact speeds as high as 200,000 RPM can be obtained with only slightly more air pressure applied. The application of air under pressure is conventional, and may be effected directly from a pump, air turbine or similar source and may be controlled by valve means, gates or other similar control means.

The spindle 12 housed within the bearing sleeve 32 and bearing mount 34 are each also supplied with air under pres sure so that a pneumatic bearing or air cushion supports the spindle, freely, during its rotation. Air under pressure is fed from the same source supplying air to cushion the turbine, through inlet passage 102 located in the cap 36 and passes via the thrust disk 28 and housing 72 into a short conduit 114 in disk 30 into an oblique conduit "6 passing through the radial collar of the bearing mount 34. The conduit 1 16 leads to a circumferential cut 118 in the interior surface of the mount 34 extending axially along substantially the length of the mount 34 from about adjacent the lower retaining ring 42 to its collar. The cut 118 is matched by a corresponding cut 120 in the outer face of the bearing housing 32. The bearing sleeve 32 is provided with a plurality of nozzle or jet like orifices 122 lead ing radially inwardly from the space defined between the cuts "6 and 118. These orifices 122 are similar to the nozzle openings 88 in the thrust disks in that they are tapered in the direction of flow to increase the pressure of the air on its bearing surface. A number (three are shown) of circumferential grooves 124, axially spaced, are provided about the exterior surface of the bearing housing 32. The grooves 124 are each connected to an axial extending duct 126 which is blind at one end but at the other extends the length of the housing 32 to exit at an opening 130 at the lower end.

Following the flow of air from inlet 102 it will be seen that air under pressure surrounds the entire surface between the bearing housing 32 and the spindle 12 forming a thin layer of air support for free rotative movement of the spindle. The air under pressure exhausts fully outwardly of the duct 126 through the opening 130. The location of orifices 122 is optional; however, it is preferred that they be arranged in circumferential rings with at least eight in each ring and each ring axially spaced from the next by a small fraction of an inch. ln

this manner, each adjoining orifice 122 divides the bearing surfaces into a multitude of separate pressure areas. Each pressure area has its own exhaust 124 that enables the pressure areas to function as a localized pressure wedge, which is extremely sensitive and reacts rapidly to compensate for forces that tend to relatively displace the shaft 12 and the housing 32. This arrangement results in an air bearing having a minimum gap, a relatively great stiffness and resistance to side movement, and that has a relatively large load carrying capacity.

The construction of the air bearing for the spindle permits the spindle to be made very small. The tolerances between the rotating spindle housing and bearing mounts may also be maintained very small. The air cushion permits the parts to rotate relatively freely without binding and with virtually all sideway swing or slippage eliminated. The small air bearing space does not allow the air to flow, thus permitting truly high speeds, with no friction or heat created. The location of what would appear to be an unusually large number of orifices I22 contributes to an even distribution of air, and an assurance of sufficient air pressure over the entire surface, no matter what side slippage occurs. Consequently, the spindle will run true in millionths of an inch over an extended period of time. The close tolerances and air flow prevents dust from fouling the rotating surfaces giving longtime service with little need for repair or costly maintenance.

The up (retracted position) and down (extended or working position) stoke of the spindle is created by actuating the air piston 56. This is accomplished by providing the chamber 54 with continuous opposed air pressure on either side of the piston 56 in double action" and by varying the relative pressure to provide either up or down movement. The up component is supplied through inlet 106 in the cap in the same manner as the other air sources are supplied. lnlet 106 communicates with a conduit 132 extending through the thrust disks 28 and 30 and leads into an oblique conduit 134 which itself leads into an axial conduit 136. The latter conduits I34 and 136 are formed in the bearing mount 34. The conduit 136 terminates at the base of the piston 56 and enters into a radial bore 138 leading into the lower portion of chamber 54. The air for the downward movement is supplied from inlet 108 in a duct network comprising ducts 140 extending through the thrust disks 28 and 30, duct 142 and duct 144 respectively obliquely and axially through the bearing mount 34. The duct 144 enters into a bore I46 at the upper edge of the piston 56. The lower and upper bores 138 and 146 connect to a circumferential groove 150 and I52 respectively cut in the outer face of the mount 34 to distribute the air more uniformly within the annular portions of the chamber 54. The pneumatic system for operating the retraction and extension of the spindle may be replaced with an analogous hydraulic system.

Thus, it will be observed that by supplying air to both the upper and lower portions of the chamber 54, the piston 56 is constantly under the influence of a positive air or hydraulic pressure. Small variations of the relative pressures in the upper and lower portions will consequently force the piston to move axially carrying with it the mount 34 and the spindle 12. Because of the double action no need arises for ratchet catch means, incremental feed advance, complicated valving for the cylinder or piston controls, exhaust valving or other controls conventional in spindle feed or advance mechanism. The stroke of the spindle, i.e., its axial movement, is dependent on the length of the chamber 54 and not on the degree of pressure exerted on the piston or spindle.

The construction further provides the advantage that the spindle is constantly under pressure which enables it to enter into the workpiece with greater ease. The back pressure exerted by the workpiece can be overcome by regulating the air pressure to the piston 56. Suitable feed back control, fixed controls or automatic controls can be used to control the downward force on the spindle via this air system. It is preferred that this air stroke be automatically regulated to provide the final feed stroke into the workpiece while the coarse or major adjustment is made by regulation of the knob 68.

The impression of air to the upper portion of chamber 54 forces the spindle down or into extended working position. The impression of air to the lower portion of the chamber forces the spindle upwardly into the housing It) to retract or take the working tool out of working position. Suitable sealing rings 154, such as O-rings, are provided about the slidable surface to prevent leakage of air from the cylinder chamber 54.

Surrounding the lower edge of the housing body 10 is an annular hollow collar 156. The body 10 is provided with a plurality of holes 158 leading into the hollow collar from the area surrounding the drill bit 18. The collar is connected via a threaded connection 160 to a vacuum source. In this manner the air surrounding the drill bit It! can be continuously exhausted withdrawing all dust and particles formed during the drilling operation. This exhaust can be made to a suitable filter for recovering of the metal and for cleansing the air. This facet of the present device has a further advantage when and should the present device he used to drill or otherwise work in an up ward position rather than downward as shown. Upward drilling is now quite common and sometimes preferred for special operations where the workpiece is easier to handle and where greater control may be obtained by handling it. In this situation, the shavings, dust and any particles which would normally fall onto the drill can be quickly carried away.

It will now thus be seen that the present invention provides a small, high speed, highly accurate and precise instrument of the rotary tool type. The tool is shown as being pneumatically operated; however, it will be clear that a hydraulic system may be substituted for it. Various other changes and modifications will suggest themselves to those skilled in this art. As a consequence, the present disclosure is intended to be merely illustrative and should not be taken as limiting, in any manner, the scope of the invention.

What is claimed is:

l. A rotary tool comprising a housing,

an elongated spindle mounted for rotation within said housing, said spindle having means at one end for releasably holding a work tool,

an air turbine comprising a rotor secured to the other end of said spindle,

a stator secured to said housing and surrounding said rotor,

said rotor comprising a wheel having a plurality of blades positioned about its periphery,

said stator having a plurality of noales for impinging air upon the blades of said wheel tangentially to the circumference of said wheel,

and means for delivering a continuous stream of air to said nozzles, a disk positioned adjacent to each side of said wheel to form a thrust surface therefore,

and means for delivering a continuous supply of air between said thrust surfaces and said turbine wheel to provide a pneumatic bearing therebetween.

2. The tool according to claim 1 including a sleeve surrounding said spindle and forming bearing therefore, and means for delivering a continuous stream of air between said spindle and said sleeve to form an air cushion therebetween.

3. The tool according to claim 2 including means for mounting said sleeve within said housing for reciprocating movement in the axial direction of said spindle, and means for regulating said movement whereby said spindle may be extended or retracted from said housing.

4. The tool according to claim 3 wherein said disks forming said thrust surfaces, said turbine stator and said spindle bearing mount are fixedly connected concentric to the axis of said spindle.

5. The tool according to claim 3 wherein said means for regulating the axial movement of said spindle comprises a pneumatic piston and cylinder assembly and means for selectively supplying air thereto.

6. The tool according to claim wherein said means for supplying air to said regulating means comprises at least one conduit adapted to be connected to a source of air extending through said thrust disks, and said spindle mount.

7. The tool according to claim 1 including an annular collar secured to said housing and spacedly surrounding the working tool holding end of said spindle, a port located in said collar and means for connecting said port to a source of suction whereby impurities may be exhausted from about said working tool.

8. An air turbine for use in miniature rotary tools having a spindle adapted to hold a working tool comprising an annular housing secured against movement, a ring secured to said housing, said ring having a plurality of air nozzle located about its circumference directed inwardly of said ring, and means for delivering air to each of said nozzles simultaneously from a continuous source thereof, and a rotor located within said ring and secured at its center to said spindle, said rotor having a plurality of air buckets located about its periphery, said ring having a plurality of reaction means located on the axial exterior surfaces thereof and extending in part over said air buckets, said nozzles being arranged so as to impinge air upon said buckets to cause said rotor to turn, said air being then reversed by said buckets to impinge on said reaction means to further cause said air to propel said rotor.

9. An air turbine for use in miniature rotary tools having a spindle adapted to hold a working tool comprising an annular housing secured against movement, a reaction ring secured to said housing, said ring having a plurality of air nozzle located about its circumference directed inwardly of said ring, and means for delivering air to each of said nozzles simultaneously from a continuous source thereof, and a rotor located within said reaction ring and secured at its center to said spindle, said rotor having a plurality of air buckets located about its periphery, each of said buckets being formed by a circumferential groove section formed in the center of the peripheral edge of said rotor and arcuate U-shaped wings extending outwardly toward the axial edges, said wings tapering from a high crest at the center of said periphery to the plane of said peripheral edge, said nozzles being arranged so as to impinge air upon said buckets to cause said rotor to turn.

10. The turbine according to claim 9 wherein the number of buckets is substantially equal to the number of nozzles.

ll. The turbine according to claim 9 wherein said nozzles are arranged to impinge air in the bight of said bucket wings at an angle tangential to said circumferential groove section.

[2. The turbine according to claim 11 wherein said reaction ring is formed with a circumferential groove extending about its outer periphery, said nozzles communicating radially with said groove, said groove communicating in turn with the source of air whereby said air is distributed evenly to all of said nozzles.

[3. The turbine according to claim 9 wherein said reaction ring is formed with a plurality of vanes arranged substantially radially inward of said turbine circumferentially about each axial side of said ring, said vanes extending over the tapered edges of said U-shaped buckets and adapted to receive air exhausting from said buckets to provide a rotating reaction therefore.

14. The turbine according to claim 13 wherein said vanes extend at an angle to the center of said turbine in the direction of rotation of said rotor.

15. The turbine according to claim l3 wherein said reaction ring is provided with a circumferential exterior shoulder communicating with said vanes, and said housing is provided with at least one exhaust port whereby air passing through said vanes may be exhausted from said turbine.

16. in a turbine comprising a housing having a fixed reaction ring, and an annular disk rotor located therein and substantially coplanar therewith, pneumatic bearing means for said rotor comprising a cover disk located on each side of said rotor and fixed to said housing, a plurality of concentric chann els located in each of said cover disks, a plurality of axially directed orifices for impinging air upon said rotor, located in each channel, a radially extending channel interconnecting each of said concentric channels, said radial channel being adapted for connection to a source of air under pressure to thereby cause air to be impinged simultaneously through said orifices onto the axial faces of said rotor.

l7. The bearing means according to claim 16 wherein said orifices are provided with restricted jet-like openings facing said annular disk rotor.

18. In a rotary tool having an elongated spindle adapted to hold a working tool, an air bearing for said spindle permitting rotary motion thereof, said air bearing comprising a sleeve surrounding said spindle and having an inner face spaced therefrom, a plurality of orifices arranged about said sleeve, a mount surrounding said sleeve, said mount being secured to said sleeve and having a cylindrical cut out portion on its inner surface spaced from said sleeve to form a cylindrical air space thereabout, each of said orifices comprising a jet nozzle extending radially through said sleeve toward the surface of said spindle, to deliver air between said spindle and to face of said sleeve said mount having conduit means connecting said cylindrical space to a source of air, whereby said air may be supplied to all of said orifices simultaneously.

[9. The air bearing according to claim 18 including at least one channel formed on the inner face of said sleeve, and conduit means within said sleeve for exhausting the air from between said sleeve and said spindle.

20. An air bearing as in claim IS, a gap defined between said sleeve and spindle, a plurality of air exhaust channels between said sleeve and spindle to exhaust air from said gap, each exhaust channel defining with certain ones of said plurality of orifices pressure areas in said gap resisting relative displacement of said spindle and sleeve. 

1. A rotary tool comprising a housing, an elongated spindle mounted for rotation within said housing, said spindle having means at one end for releasably holding a work tool, an air turbine comprising a rotor secured to the other end of said spindle, a stator secured to said housing and surrounding said rotor, said rotor comprising a wheel having a plurality of blades positioned about its periphery, said stator having a plurality of nozzles for impinging air upon the blades of said wheel tangentially to the circumference of said wheel, and means for delivering a continuous stream of air to said nozzles, a disk positioned adjacent to each side of said wheel to form a thrust surface therefore, and means for delivering a continuous supply of air between said thrust surfaces and said turbine wheel to provide a pneumatic bearing therebetween.
 2. The tool according to claim 1 including a sleeve surrounding said spindle and forming bearing therefore, and means for delivering a continuous stream of air between said spindle and said sleeve to form an air cushion therebetween.
 3. The tool according to claim 2 including means for mounting said sleeve within said housing for reciprocating movement in the axial direction of said spindle, and means for regulating said movement whereby said spindle may be extended or retracted from said housing.
 4. The tool according to claim 3 wherein said disks forming said thrust surfaces, said turbine stator and said spindle bearing mount are fixedly connected concentric to the axis of said spindle.
 5. The tool according to claim 3 wherein said means for regulating the axial movement of said spindle comprises a pneumatic piston and cylinder assembly and means for selectively supplying air thereto.
 6. The tool according to claim 5 wherein said means for supplying air to said regulating means comprises at least one conduit adapted to be connected to a source of air extending through said thrust disks, and said spindle mount.
 7. The tool according to claim 1 including an annular collar secured to said housing and spacedly surrounding the working tool holding end of said spindle, a port located in said collar and means for connecting said port to a source of suction whereby impurities may be exhausted from about said working tool.
 8. An air turbine for use in miniature rotary tools having a spindle adapted to hold a working tool comprising an annular housing secured against movement, a ring secured to said housing, said ring having a plurality of air nozzle located about its circumference directed inwardly of said ring, and means for delivering air to each of said nozzles simultaneously from a continuous source thereof, and a rotor located within said ring and secured at its center to said spindle, said rotor having a plurality of air buckets located about its periphery, said ring having a plurality of reaction means located on the axial exterior surfaces thereof and extending in part over said air buckets, said nozzles being arranged so as to impinge air upon said buckets to cause said rotor to turn, said air being then reversed by said buckets to impinge on said reaction means to further cause said air to propel said rotor.
 9. An air turbine for use in miniature rotary tools having a spindle adapted to hold a working tool comprising an annular housing secured against movement, a reaction ring secured to said housing, said ring having a plurality of air nozzle located about its circumference directed inwardly of said ring, and means for delivering air to each of said nozzles simultaneously from a continuous source thereof, and a rotor located within said reaction ring and secured at its center to said spindle, said rotor having a plurality of air buckets located about its periphery, each of said buckets being formed by a circumferential groove section formed in the center of the peripheral edge of said rotor and arcuate U-shaped wings extending outwardly toward the axial edges, said wings tapering from a high crest at the center of said periphery to the plane of said peripheral edge, said nozzles being arranged so as to impinge air upon said buckets to cause said rotor to turn.
 10. The turbine according to claim 9 wherein the number of buckets is substantially equal to the number of nozzles.
 11. The turbine according to claim 9 wherein said nozzles are arranged to impinge air in the bight of said bucket wings at an angle tangential to said circumferential groove section.
 12. The turbine according to claim 11 wherein said reaction ring is formed with a circumferential groove extending about its outer periphery, said nozzles communicating radially with said groove, said groove communicating in turn with the source of air whereby said air is distributed evenly to all of said nozzles.
 13. The turbine according to claim 9 wherein said reaction ring is formed with a plurality of vanes arranged substantially radially inward of said turbine circumferentially about each axial side of said ring, said vanes extending over the tapered edges of said U-shaped buckets and adapted to receive air exhausting from said buckets to provide a rotating reaction therefore.
 14. The turbine according to claim 13 wherein said vanes extend at an angle to the center of said turbine in the direction of rotation of said rotor.
 15. The turbine according to claim 13 wherein said reaction ring is provided with a circumferential exterior shoulder communicating with said vanes, and said housing is provided with at least one exhaust port whereby air passing through said vanes may be exhausted from said turbine.
 16. In a turbine comprising a housing having a fixed reaction ring, and an annular disk rotor located therein and substantially coplanar therewith, pneumatic bearing means for said rotor comprising a cover disk located on each side of said rotor and fixed to said housing, a plurality of concentric channels located in each of said cover disks, a plurality of axially directed orifices for impinging air upon said rotor, located in each channel, a radially extending channel interconnecting each of said concentric channels, said radial channel being adapted for connection to a source of air under pressure to thereby cause air to be impinged simultaneously through said orifices onto the axial faces of said rotor.
 17. The bearing means according to claim 16 wherein said orifices are provided with restricted jet-like openings facing said annular disk rotor.
 18. In a rotary tool having an elongated spindle adapted to hold a working tool, an air bearing for said spindle permitting rotary motion thereof, said air bearing comprising a sleeve surrounding said spindle and having an inner face spaced therefrom, a plurality of orifices arranged about said sleeve, a mount surrounding said sleeve, said mount being secured to said sleeve and having a cylindrical cut out portion on its inner surface spaced from said sleeve to form a cylindrical air space thereabout, each of said orifices comprising a jet nozzle extending radially through said sleeve toward the surface of said spindle, to deliver air between said spindle and to face of said sleeve said mount having conduit means connecting said cylindrical space to a source of air, whereby said air may be supplied to all of said orifices simultaneously.
 19. The air bearing according to claim 18 including at least one channel formed on the inner face of said sleeve, and conduit means within said sleeve for exhAusting the air from between said sleeve and said spindle.
 20. An air bearing as in claim 18, a gap defined between said sleeve and spindle, a plurality of air exhaust channels between said sleeve and spindle to exhaust air from said gap, each exhaust channel defining with certain ones of said plurality of orifices pressure areas in said gap resisting relative displacement of said spindle and sleeve. 